A prosthesis limb replaces a missing extremity, such as an arm or a leg and may be needed for a variety of reasons, including diseases, and accidents. An artificial limb may also be needed when a person is born with a missing or damaged limb(s). The type of prosthesis limb used is determined largely by the extent of an amputation or loss and location of the missing limb. A transtibial prosthesis is an artificial leg that is attached to a user below the knee and includes a lower leg, ankle and foot. The transfemoral prosthesis is an artificial leg that is attached to the user's amputated limb above the knee and includes an upper leg and mechanical knee. A transradial prosthesis is an artificial arm that is attached to the user below the elbow and includes a forearm and hand. A transhumeral prosthesis is an artificial arm that is attached to the user above the elbow.
In developing areas of the world, including large portions of Africa, the leading causes of amputations are industrial, vehicular, and war related accidents. In more developed areas, such as North America and Europe, the leading causes for the amputations are diseases including cancer, infection and circulatory. In the United States, approximately 100,000 legs are lost each year to diabetes, vascular disorder, accidents and cancer. Because there are so many amputations, there is a substantial need for prosthetic limbs.